Friday, 28 October 2016

Types of active suspension (Il). Pneumatics for the Audi A8

Audi A8 air suspension 

Air suspension allows the body to be adjusted to different heights in accordance with running requirements, it also helps the suspension and damping to adapt to the road surface and driving style.

This suspension is noted for its high flexibility, good oscillation absorption and for the self-regulation of the system that allows the distance between the chassis and the surface of the road to be maintained irrespective of the vehicle's load.

With the aid of vertical acceleration sensors on the body, this suspension model recognises the ground configuration. The driving style can be ascertained based on the vehicle's speed and the steering angle.

Three different damping programs can be selected, auto, comfort and sport. Each one is activated depending on road conditions and the driver's wishes, and contributes to driving safety and comfort. Air suspension with adaptive damping also allows each damper to be controlled independently.

Primarily, air suspension is made up of an air supply unit that generates and builds up the pressure necessary for operating the circuit, level sensors for height regulation, air springs and a warning light on the instrument cluster.

The air supply unit includes a control unit, a compressor with filter drier and discharge valves, a relay for the compressor and some suspension valves.

The supply unit supplies air to the air springs through the valve unit until the vehicle level is adjusted. The control unit is informed of this level by the measurements provided by the level sensors.
Each suspension block is controlled by a solenoid valve, which opens and closes the link with the circuit. The suspension solenoid valves are electrically energised in pairs, front axle and rear axle.
Two operation times are taken into consideration for the operation of the circuit. One of these is the pressurisation time, when the air is compressed to provide the flow to the solenoid valves that control the air springs, the excess air goes to the accumulator through its solenoid valve.
The other operation time is the depressurisation period. Both the suspension block solenoid valves and the discharge solenoid valves are opened. This latter valve allows the air to flow to the outside after crossing the additional silencer and the air filter.

Sensor, management and actuator diagram 

You may also be interested in: Active suspensions - part 1 


  1. The role of suspension in our vehicle is really appreciable, it helps connect the wheels with the vehicle. Therefore, in different vehicle models, we have found different types of suspensions and especially in luxury vehicles like Audi, BMW, and many others, we have found a special suspension system which is known as air suspension. Thanks for such a wonderful review.
    Audi Service Russian Hill, CA

  2. This blog has a chock-a-block of useful information about car suspension. You are right that both the suspension block solenoid valves and the discharge solenoid valves are opened. Thanks.


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